Which mailbox providers use Spamhaus listings to block email and how does it affect deliverability?

Marketer from Email Geeks shares that Gmail doesn't officially do so, but they suspect that Gmail factors listings into reputation scores indirectly.

Marketer from Email Geeks responds that it could be prudent to assume that they all use it, and just stay off Spamhaus and other lists.

Marketer from Email Geeks shares they are fairly confident that Apple uses DBL data in their filtering.

Email marketer from Litmus explains that blocklists like Spamhaus are used by ISPs and mailbox providers to identify and filter spam. If your IP address or domain is listed, your emails may be blocked, go to the spam folder, or experience delayed delivery, significantly impacting your email marketing results.

Email marketer from EmailonAcid recommends regularly monitoring blocklists like Spamhaus to quickly identify and address any listing issues. Proactive monitoring helps prevent deliverability problems before they significantly impact email campaigns.

Marketer from Email Geeks shares Road Runner used to, and included a direct link to the Spamhaus listing in the SMTP reject message.

Email marketer from Reddit shares that many smaller ISPs and hosting providers heavily rely on Spamhaus for their spam filtering, even if major providers have more sophisticated systems. Therefore, being listed on Spamhaus can cause widespread issues beyond just the big mailbox providers.

Email marketer from Email Marketing Forum shares an anecdote about a client who experienced a sudden drop in email deliverability due to a Spamhaus listing. The client had to work with Spamhaus to resolve the issue, which took several days and caused significant disruption to their email marketing efforts.

Email marketer from Gmass explains that a listing will prevent emails from arriving to the recipients inbox. If you send email to a large number of people your email could get blocked and/or marked as spam.

Email marketer from StackOverflow explains that when an IP address is listed on Spamhaus, numerous mail servers will refuse to accept connections from it. This causes bounces and delayed delivery until the IP is removed from the list.

Marketer from Email Geeks explains that you're not likely to find a comprehensive list of mailbox providers that use Spamhaus because they keep their methods confidential.

Email marketer from Mailjet shares that while not all mailbox providers publicly disclose their reliance on Spamhaus, many use it as one factor in determining sender reputation. A poor reputation due to Spamhaus listings can negatively affect deliverability, causing emails to be filtered or blocked.

Email marketer from GlockApps states that to check if a domain or IP is on a blocklist send a test email with their test. If the email doesn't reach the inbox it could be caused by blocklists. GlockApps uses this to test it's own emails.

Email marketer from SendPulse notes that major mailbox providers such as Gmail, Yahoo, and Microsoft (Outlook, Hotmail) use Spamhaus data to some extent, although their exact methods are not public. Being listed on Spamhaus can lead to significant deliverability issues with these providers.

Expert from Spam Resource explains that spam traps can lead to IPs being added to blocklists such as Spamhaus. Email marketers should check for spam traps in their campaigns to prevent this from happening.

Expert from Email Geeks shares that they compiled a list of ISPs using Spamhaus based on client bounces during their Salesforce days. They recall that Yahoo used to, Comcast does, and Microsoft does (possibly), while Apple is uncertain. Gmail doesn't explicitly say they do, but Al suspects they consume reputation data from Spamhaus.

Expert from Word to the Wise responds that blocklists like Spamhaus are used by ISPs and mailbox providers, with some using them more heavily than others. A listing will result in significant deliverability problems, ranging from emails going to spam to being completely blocked.

Documentation from Digital Ocean suggests checking if your IP is on any email block lists. Digital Ocean also advises using a tool like MultiRBL.valli.org to help identify this

Documentation from Google says that while they don't specifically mention Spamhaus, they do state that they use various signals to identify spam, and being listed on reputable blocklists can negatively affect deliverability to Gmail users. Following their bulk sender guidelines is recommended.

Documentation from Spamhaus details the reasons for listing an IP address or domain, including spamming activity, malware distribution, or hosting phishing sites. If a network has any of these issues, it can be listed, affecting all email sent from that network.

Documentation from Spamhaus explains that the SBL lists IP addresses involved in spamming or other malicious activities, and many mailbox providers use it to filter incoming emails. Being listed on the SBL can severely impact deliverability, leading to emails being blocked or sent to the spam folder.

Documentation from Microsoft says that they use various block lists, including Spamhaus, as part of their filtering process for Outlook and Hotmail. Senders listed on these lists may experience delivery problems, and it is recommended to follow best practices to avoid being listed.